The star cluster formed inside the 150-light-year-wide cloud of gas and dust. Even as stellar winds push open the cavity, they compress material near the center of the hollow, spurring new stars to form.

Image courtesy NASA/JPL-Caltech/UCLA

Aurora Ahoy

For his one-thousandth tweet from space, Japanese astronaut Soichi Noguchi sent his followers a picture taken as the International Space Station was about to fly through an aurora at 17,400 miles (28,000 kilometers) an hour on April 5, 2010.

When the space shuttle Discovery docks with the space station this week, Naoko Yamazaki will join Noguchi aboard the station, marking the first time two Japanese astronauts have served together on the craft.

Spitzer will be studying changes in the Orion Nebula's stars as part of its "warm" mission, which started when the craft's liquid coolant ran out in May 2009. Some instruments won't operate without being chilled, so mission managers are adjusting how they use Spitzer's equipment.

Image courtesy NASA/JPL-Caltech

Space Station on the Moon

Looking like a fly on the camera lens, the International Space Station makes a bright white dot against the moon in a picture taken from Kennedy Space Station in Florida on April 5, 2010.

In infrared light the nebula known as Gum 19 appears bright on one side and dark on the other, because hydrogen gas on the right is being heated and charged by radiation from a supergiant blue star inside.

Unseen in the new picture—released March 31, 2010, by the European Southern Observatory—new stars are forming in the boundary between light and dark.